Pneumatic dispatch system



Oct. 8, 1935. J. M. SCANLAN PNEUMATIC DISPATCH SYSTEM 2 Sheet-Sneet 1Filed Sept. 20, 1932 1935 J. M. SCANLAN PNEUMATIC DISPATCH SYSTEM FiledSept. 20, 1952 2 Sheets-Sheet 2 INVENTOR Zz /AWZ ATTORNEY Patented Oct.8, 1935 UNITED STATES PATENT OFFICE by mesne assignments, to The Lamson"Com.-

pany, Syracuse, N. Y., a corporat'ibn'of Massachusetts ApplicationSeptember 20, 1932,.Serial-Ne. 633,951.

8 Claims. (01'. 2243-28).

This invention relates to pneumatic dispatch systems: in which carriersare propelled from one point to another in the same building or in adjoining buildings by reason of a differential pres-- 5' sure created inthe systems. It has particular reference to systems of sort adapted forthe transmission of comparatively large carriers such as employed in thedelivery of documents and the like although it is also applicable to theSmaller carrier systems whether operated by suction or pressure.

In the operation of pneumatic dispatch systerns especially of the largecarrier type it has been found objectionable toattempt to transmit thecarriers while the pressure difierential is largely interfered: with ordestroyed by the opening of a discharge door associated with theparticular sending tube to be used or by the presence of another carrierin the line. Such an attempt isparticularly objectionable in connectionwith lines which are commonly known as downsends", i. e'., in which asubstantial drop occurs in the line at a point near the dispatching endof the same. When carriers are permitted tobe inserted freely into tubesof this sort there is a danger that several carriers: may become piledup at the lower end of a drop in the line while the discharge door isleft open, for example, for an unduly long time. Under various othercondi- 301 tions; also, it becomes desirable to know at one point oranother along the line whether a tube is in the line, either in transitor awaiting removal at the discharge end.

It has been a primary object of the present invention toovercomethedifiiculties' previously encountered by theprovision of the automaticmeans for indicating when a carrier is intransit era-waitingremoval. Inone form of the invention; as applied to a vacuum system, the desiredindication is given by preventing the" insertion of a carrierinto a lineso long as thepressuretherein adjacent the inlet is maintained atsubstantially atmospheric by virtue of some obstruction in the lineor-due to the opening of the discharge door. To accomplish this result apneumatically operated stop is provided, and it is withdrawn only uponthe establishment of a substantial dif ference in pressure between theinside of the tube and the outside atmosphere.

In lieu of operating a stop the devices contemplated bythe presentinvention may bemade tosimply control a signal as-indi'catedl The samesystem may be employed; if desired, to operate an indicator inconjunctionwith a long line, for

example, which provided with a plurality of inlets. The: indicator may,vin that case, notify operator at onepoi nt that a carrier is in' theline at. a; point more: remote from the terminal so that no carriershould beinserted. A stop may. be providediin' this case inlieu of theindi- 5.

cater so as: tepo'sitiyely prevent introduction of a carrier' under the:conditions mentioned. A further application ot the invention may be madein. connection the removal of. carriers from a pressure systena- It. a.carrier is permitted to 10 remain at the discharge end of a pressuretube it may cause such a back. pressure tobe built up as to interferewiththe transmission of another carrier. 1-,. therefore,v contemplatethe provision 0t an automatic signal. adapted. to give a continu- 15 ousindication so long as a-carrier remains at the discharge terminal;

Other. objects;andv advantages of the invention will: appear irons adetailed. description of an illustrative embodiment. otthe same whichwill now 20 be givenin. eoniunction. with the accompanying drawings,inwhich;

Figure I. is a-more. or less diagrammatic view of. a. pneumatictransmission tube partly broken away showing the inlet and dischargeends of 25 the same;

' Figure. 2 is a vertical). longitudinal, sectional View through theinlet portion of the tube;

Figure 3"i's a transverse sectional view through the tube nearthe inlettakenalo'ng the line 3-3 of Figure 2:

Figure 4 is a. diagrammatic view showing the connections at. thedischarge end of the tube;

Figureeis a; diagrammatic view of a: signal applied to a modified formof system, and

Figure 6" is adiagrammatieview indicating a furtherapplicatibn of theinvention.

Referring now'to Figures 1 to 4 of the drawings, the transmissiontube F0may be of the usual construction as preferably employed in connec- 40't'i'onwi'ththe transmission of largecarriers. As best shown in Figure 31it is preferably elliptical in cross section so'as'to" adapt it" toreceive carriers or the sameness-sectional form; A bell end llmaybeproviued at theinlet of the tube for the reception of the carriersto be transmitted while an'en'larged" chamber or compartment l2 maybeprovid'err at the discharge end of the: tube in which the accumulationof a number of carriersmay bepermitted. 1 When the invention is appliedto a suction or vacuum systems the lower or discharge: end of the tubemay lie-connected by'a; branch line l3 to asuitable suction drum. I 4from which the air is constantly evacuated, in a manner well known. Adoor I5 may be provided at the front of the chamber I2 to permit removalof the carriers as they are discharged into the chamber. In the handlingof smaller carriers, such as employed on cash-carrier systems, it isgenerally the practice to discharge the carriers directly into an openreceptacle. This is notalways considered practicable, however, in thehandling of larger carriers since the force and consequent noise withwhich they would be discharged into an open receptacle would beexcessively great. Accordingly, it is necessary in such a system todischarge the carriers into a closed chamber and the operator at thepoint of delivery must open the door of the chamber whenever a carrieris to be removed. At such a time it is impossible to establish anyappreciable degree of vacuum or suction within the tube I0 due to thefact that. the suction line I3 will be placed in substantially opencommunication with the outside atmosphere through the chamber I2 and thedoor I5. It is undesirable under these circumstances to insert a carrierinto the tube, particularly where the tube is provided with a suddendrop or downsend adjacent the inlet end. If the door I5 were held openfor a sufiiciently long time, due to carelessness, or for other reasons,there would be danger of permitting an accumulation of several carriersat the bottom of the down-send with consequent danger of doing damage tothe carriers and of clogging the system by virtue'of the fact that thesuction when later developed, upon closing of the door, would beinsufficient to cause a movement of all of the accumulated carriers.

In order to avoid the danger of a misoperation of the sort mentioned,astop I6 is extended through an opening in the wall of the tube at apoint adjacent the inlet of the tube. This stop is so situated that acarrier II, a portion of which is shown in dotted lines in Figure 2, maynormally be introduced a slight distance but may not be fully introducedor be drawn into the tube until the stop has been displaced. In order toautomatically remove the stop I6 from the path oi the carrier wheneverthe tube is in condition for the pneumatic transmission of the carrier,a disc or plunger I8 is attached to the upper end of the stop. Normallythe weight of this disc and the stop will serve to carry the latter intothe position shown in Figure 2. However, under the conditions which willbe mentioned, the disc I8 may be made to rise in the chamber I9 and thuscause withdrawal of the stop from the path of the carrier.

The under surface of the disk I8 is in constant communication with theoutside atmosphere through an opening 20 provided at the front of thehousing 200 which encloses the stop mechanism. The upper surface of thedisk I8 is in communication through an opening 2| and a passage 22through the casing 200 with the interior of the tube Ill. Now, undernormal conditions the minimum flow of air through the tube III, which isordinarily provided, is insufiicient to cause a pressure differential onthe two sides of the disc I8 which will be great enough to lift thelatter. However, when a carrier is inserted in the bell II at the inletof the tube, suitable mechanism, whichis well known in installations ofthis type but is not shown in the drawings, will be brought into play togreatly increase the suction and thus create a partial vacuum ofsufiicient magnitude to cause transmission of the carrier through thetube. The vacuum created at this time, acting through the passage 22 andthe opening 2|, establishes such a difference in pressure between thetwosides of the disc I8 that the stop IE will be quickly raised out ofthe path of the carrier and will permit the latter 5 to be drawn throughthe tube.- It will be obvious that if at the time the carrier isinserted in the bell II the door I5 is held open by the operator at thedischarge end of the tube, the partial vacuum will not be set up in thetube It and hence 10 r the stop I6 will not be withdrawn. As soon as thedoor I5 is closed, however, the vacuum will be established in the mannerindicated and withdrawal of the stop will take place. In a similar Wayif a preceding carrier is still within the tube 15 I9 and serves toprevent the establishment of a sufiicient vacuum near the inlet end ofthe tube and in the passage 22, the stop I5 will not be withdrawn.

Referring now to Fig. 5, a modified arrange- 20 ment is diagrammaticallyindicated. The tube 25 may be a portion of a continuous line formingpart of a vacuum system. It may, for example, be an intermediate sectionof a transmission line adjacent one of a plurality of inlets throughwhich 25 carriers may be introduced into the line. It Would be quiteundesirable to place a carrier into the line at an intermediate point ifanother carrier is already in transit from a point further out in theline. In the first place opening of the inlet door to admit the secondcarrier would interfere with the suction acting upon the first carrierand might cause it to drop if it were moving up- Wardly in a verticalrise in the line. Furthermore, there would be danger that the twocarriers 35 would collide at the point where the branch through whichthe second carrier is inserted merges with the main line. To avoid thesedangers I provide a small branch 26 from the main line leading to achamber 21 at one side of a dia- 40 phragm 28. The chamber 29 at theopposite side of the diaphragm may be in communication with theatmosphere through an opening 30. A stem or rod 3| connected at one endto the diaphragm may be connected at its opposite end to a contact 45member 32. One end of this member may be connected with a source ofcurrent 33 in series with an indicator 34. When a carrier is in the line25 beyond the point of connection of the branch 26, a partial vacuumwill be created in 50 the chamber 21 and the diaphragm will be lifteduntil the member 32 engages a contact 35 and thus closes the circuitthrough the indicator. The latter will be energized so long as thepressure in the line is maintained sufiiciently below 55 atmospheric. Asthe carrier passes the inlet of the branch 26 the suction will berelieved and the indicator circuit will be broken. Branch 26 maycommunicate with the main line at any convenient point, as at a pointnear one of the intake 0 terminals or at a point near the discharge endof the line. In the latter case a single diaphragm unit may control theoperation of a series of indicators, one located at each of the intakepoints, and these will then be active throughout the 55 transit of acarrier. If desired, the indicator may be replaced by a stop, such asshown in Fig.

2, particularly if the diaphragm structure is located adjacent one ofthe intake branches, or the stop may be electrically operated by amagnet 7 energized in lieu of the indicator 34.

In Fig. 6 a further modification is shown. The transmission line 36 maybe considered as part of a pressure system and may be provided with adischarge terminal 31. A carrier 38, indicated in 75 dotted lines, isadapted to extend into the tube a short distance until it is actuallyremoved from the discharge end. In this way so long as it is left in theline it will create a back pressure. A branch 39 communicating with achamber 40 on one side of a diaphragm 4| will transmit the back pressureto the diaphragm and lift the same against the atmospheric pressure inthe chamber 42 which is in communication with the outside through a port43. The diaphragm is connected with a contact arm 44 which is in serieswith a source of current 45 and an indicator 4B of any suitable type.When the diaphragm is lifted it will carry the arm 44 into engagementwith a contact 41 to close the circuit through the indicator, which willremain energized until the carrier is removed. A series of indicatorsmay be provided, if desired, one at each of a plurality of sendingpoints.

While several forms of the invention have been disclosed in considerabledetail, it is to be understood that various other modifications thanthose directly suggested may be made without departing from the generalspirit and scope of the invention as defined by the claims.

What I claim is:

1. In a pneumatic dispatch system, a transmission tube having inlet anddischarge ends, means for producing a partial vacuum within said tube, astop effective under normal minimum flow conditions for preventing thetransmission of a carrier through said tube, and pneumatic meanscontrolled by the pressure within said tube for withdrawing said stopWhenever a suflicient vacuum is attained within the tube.

2. In a pneumatic dispatch system, a transmission tube having inlet anddischarge ends, means for creating a differential pressure between theinterior of said tube and the outside atmosphere, a stop adjacent theinlet of said tube for normally preventing the transmission of a carrierthrough said tube, and pneumatic means in free communication with saidtube controlled by the pressure within said tube for operating saidstop- 3. In a pneumatic dispatch system, a transmission tube havinginlet and discharge ends, means for creating a differential pressurebetween the interior of said tube and the outside atmosphere, a stopeffective under normal minimum flow conditions for preventing thetransmission of a carrier through said tube, and pneumission tube havinginlet and discharge ends, 5

means for producing a partial vacuum within said tube, a stop adjacentthe inlet of said tube for normally preventing the transmission of acarrier through said tube, and pneumatic means in free communicationwith said tube for disabling said 10 stop whenever a predetermineddegree of vacuum is established.

5. In a pneumatic dispatch system, a transmission tube having a normallyopen inlet and a normally closed discharge opening, means for ar- 15resting a carrier when it is partially inserted in said inlet, means forestablishing a partial vacuum in said tube when the carrier is partiallyinserted, and means for disabling said arresting means when said partialvacuum is established.

6. In a pneumatic dispatch system, a transmission tube having a normallyopen inlet and a normally closed discharge opening, means for arrestinga carrier when it is partially inserted in said inlet, and means fordisabling said arresting 25 means when a carrier is partially inserted,said disabling means being rendered inoperative when the discharge endof said tube is opened.

7. In a pneumatic dispatch system, a transmission tube having a normallyopen inlet and a. 30 normally closed discharge opening, means forarresting a carrier when it is partially inserted in said inlet, meansfor creating a minimum flow of air through said tube, said meansproviding a carrier propelling pressure differential upon partialinsertion of a carrier, and pneumatic means operable upon establishmentof said carrier propelling pressure differential to disable saidarresting means.

8. In a pneumatic dispatch system, a transmission tube having a normallyopen inlet and a normally closed discharge opening, means for arrestinga carrier when it is partially inserted in said inlet, means forestablishing a partial vacuum in said tube when the carrier is partiallyinserted, 45 and a disc exposed on one side to the atmosphere and on theother side to the pressure within said tube for disabling said arrestingmeans when said partial vacuum is established.

JOSEPH M. SCANLAN.

